Propagate this-specialization to regular (megamorphic) calls

runtime/vm/flow_graph.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/flow_graph.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cha.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/flow_graph_compiler.h"
@@ skipping 1978 matching lines @@
       Instruction* current = it.Current();
       if (current->HasUnmatchedInputRepresentations()) {
         // Can't canonicalize this instruction until all conversions for its
         // inputs are inserted.
         continue;
       }
 
       Instruction* replacement = current->Canonicalize(this);
 
       if (replacement != current) {
-        // For non-definitions Canonicalize should return either NULL or
-        // this.
-        ASSERT((replacement == NULL) || current->IsDefinition());
-        ReplaceCurrentInstruction(&it, current, replacement);
         changed = true;
+
+        if (current->IsInstanceCall()) {
+          current->AsDefinition()->ReplaceWith(replacement->AsDefinition(),
+                                               &it);
+        } else {
+          // For non-definitions Canonicalize should return either NULL or
+          // this.
+          ASSERT((replacement == NULL) || current->IsDefinition());
+          ReplaceCurrentInstruction(&it, current, replacement);
+        }
       }
     }
   }
   return changed;
 }
 
 
 // Optimize (a << b) & c pattern: if c is a positive Smi or zero, then the
 // shift can be a truncating Smi shift-left and result is always Smi.
 // Merging occurs only per basic-block.
@@ skipping 215 matching lines @@
                                                 Representation rep,
                                                 intptr_t cid) {
   ExtractNthOutputInstr* extract =
       new (Z) ExtractNthOutputInstr(new (Z) Value(instr), index, rep, cid);
   instr->ReplaceUsesWith(extract);
   InsertAfter(instr, extract, NULL, FlowGraph::kValue);
 }
 
 
 }  // namespace dart